As a cutting insert (hereinafter referred to as “insert” in some cases), a cutting insert 20 whose main edge 46 is inclined has heretofore been disclosed in, for example, FIG. 4 of Japanese Unexamined Patent Publication No. 2008-544872. It is preferable to incline the main edge 46 from the standpoint of decreasing cutting resistance.
However, the disadvantage of poor fracture resistance occurs because the thickness of the cutting insert 20 (the distance between a first end face 28 and a second end face 30) is decreased with increase in inclination of the main edge 46.
Hence, there is a demand for a cutting insert exhibiting a low cutting resistance and excellent fracture resistance.